-Each corner has a chipboard reinforced corner. You need to Recess these to the thickness of the first sheet of acrylic. I used a stanley knife but a chisel would probably have been much safer. Keep measuring as you go and check each corner by replacing the clear Acrylic sheet. If you chisel any of the corners to much then you can always build them up again with the cut away section of table top and some PVA.
(Tip: Use the protective coating from the acrylic to help you remove it from the table top)
-When the corner reinforcements are complete paint the whole thing white with emulsion or gloss. It might not seem that important but it makes a HUGE difference.